In the treatment of various diseases, percutaneous access to the peritoneal cavity is necessary. An example is peritoneal dialysis which is often indicated for acute or chronic renal failure. To effect dialysis through the peritoneal cavity, a percutaneous passage is surgically formed through the cutaneous and subcutaneous tissues, rectus muscle and through the peritoneum itself. This passage permits insertion and implantation of a distal portion of the catheter within the peritoneal cavity. A separate caudally directed tunnel is then formed through the subcutaneous and cutaneous tissues with a tunnel exit site in the suprapubic region of the external abdominal wall. A proximal portion of the catheter is inserted into the tunnel thereby maintaining an end of the proximal portion in a downward direction along the abdominal wall. Examples of catheters used in peritoneal dialysis are disclosed in U.S. Pats. Nos. 3,633,585; 4,184,497; 4,278,092; 4,279,252; 4,392,855; 4,687,471 and 4,772,269.
A significant problem with peritoneal dialysis catheters is the risk of post-operative infection, typically infection of the tunnel and of the tunnel exit site. The prior art has attempted to address this problem by use of "swan neck" catheters which are disclosed in U.S. Pats. No. 4,687,471 and 4,772,269. (Twardowski '471 and Twardowski '269, respectively). In swan neck catheters, the distal and proximal portions of the catheter are joined by an arcuately bend segment which caudally directs the distal portion of the catheter within the peritoneal cavity and downwardly directs the proximal portion of the catheter along the external abdominal wall. By caudally directing distal and proximal portions, it is suggested that tunnel infection and tunnel exit site infection is reduced. Twardowski '269 discloses that the bend segment defines an arc range of 100.degree. to 180.degree. and that such bend segment be permanently molded into the catheter so that it is maintained when the catheter is in a natural unstressed condition. Twardowski '269 suggests that such molded bend segment minimizes upward migration of the distal end portion of the catheter in the peritoneal cavity caused by the elastic memory of linear catheters having no molded bend segments.
Notwithstanding the suggestions of Twardowski '269, some patients having swan neck catheters continue to experience some tunnel infection and tunnel exit site infection. Migration of the distal portion of the catheter within the peritoneal cavity and proximal portion within the tunnel, because of ineffective anchoring of the catheter to the tissue, is believed to be the cause. Twardowski '269 and Twardowski '471 disclose porous cuffs on both the distal and proximal portions of the catheter to promote tissue ingrowth and anchoring. However, such cuffs do not fully anchor the catheter to the tissue within the patient. Due to the fatty characteristics of subcutaneous tissue, the porous cuff on the proximal portion of a swan neck catheter does not provide adequate tissue ingrowth to anchor the catheter to the subcutaneous tissue. However, it has been observed that rectus muscle tissue results in effective ingrowth into and through the porous cuff carried on the distal portion of prior art catheters.
A problem with the prior art distal portion cuffs is evident from FIG. 7 of Twardowski '471. This drawing discloses that the porous cuff on the distal portion of the catheter extends into only part of the rectus muscle. Further, the cuff passes angularly through the rectus muscle. This results in ineffective tissue ingrowth into the porous cuff in order to anchor the distal portion in the rectus muscle. Further, the distal and proximal portions of swan neck catheters are planar so that any external force exerted on the proximal portion directly dislodges the distal portion.
To enhance securement of the distal portion to the rectus muscle, the swan neck catheter of Twardowski '471 requires the use of a flange and button anchoring device which is sutured to the posterior sheath of the rectus muscle. The use of such an anchoring device not only complicates the catheter implantation procedure, but also invites necrosis of the rectus muscle tissue.
Hence, prior to the development of the present invention, a need existed for a catheter for percutaneous access to the peritoneal cavity in which distal and proximal portions of the catheter are caudally directed to eliminate tunnel infection and tunnel exit site infection. Further, a need existed for a peritoneal dialysis catheter which would securely anchor within the rectus muscle tissue without use of anchoring beads or flanges. A need also existed for a peritoneal dialysis catheter in which the distal and proximal portions of the catheter were non-planar to thereby function as a safeguard from inadvertent dislodging of the catheter from the patient.